Truss for bridges



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J. E. GREINER. TRUSS FOR BRIDGES, HOOPS, 850.

- Ive/535,695. Patented-Mar. 12-, 1895.

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JOHN EDVIN GREINER, OF BALTIMORE, MARYLAND.

TRUSS FOR BRIDGES, ROOFS, &.C.

SPECIFICATION forming part of Letters Patent No. 535,695, dated March12, 1895.

Application filed September 10, 1894- Serial No. 5 21 (N0 m l- To allwhom it may concern:

Be it known that I, J OHN EDWIN GREINER, of Baltimore, Maryland, haveinvented certain new and usefullmprovements in Bridges, Roofs, or otherStructural Work; and I do hereby declare the following to be a clear,full, and exact description thereof, reference being had to theaccompanying drawings and to the letters of reference marked thereon. 1

My invention relates to a new form of subdivided quadrangular ortriangular bridgeor roof truss having but one support on each pier andhaving some of the maininclined.

web members which pass from chord to chord, and are connected directlythereto, intersect two or more panels, but instead of being in astraight line between the chords as is the case in ordinary subdividedtrusses, these inclined members have their points of intersection withthe upper chord, lower chord. and verticals, on the line of a curve, ascan be seen by the accompanying drawings, in which- Figure 1 representsa detailed elevation of theimproved truss having eight panels. Theinclined web members starting from the cen ter panel point of upperchord intersect two panels. This is designed as a truss for a throughbridge the bearings on masonry being directly under the ends of thebottom chord. Fig. 2 represents a skeleton elevation of a truss havingan odd number of panels, in which the inclined members intersecting twopanels, start from the joints on the bottom chord nearest the center ofthe-bridge. Itis designed as a truss for a deck bridge, the hearings onmasonry being directly under ends of upper chord. Fig. 3 represents askeleton elevation of a truss in which the inclined web membersbeginning with the center joint of the lower chord, intersect threepanels designed for a through bridge.

Viewing Fig. 1, it will be observed that the improved truss as thereshown, is composed of an upper chord A, a lower chord B, inclined webmembers 0 intersecting one panel, inclined web membersD which join onechord at the center joint and intersect two panels before joining theother chord at an intermediate panel point free from the abutments,hangers or verticals E outside of the bow formed by inclined members D,counter braces G, and verticals F included within the bow of theinclined members D. The counter braces G, which are joined at one end tothe lower chord, are secured to the inclined web members D at theirintersection with the verticals F, and their object is to take up thestrains due to a moving load and to hold the inclined web members firmlyin position. They are not strained under a uniformly distributed load.

In Fig. 2 is seen the improved truss when there is an odd number ofpanels. In this case, the main inclined diagonals D, start from thepanel point on lower chord nearest the center of the bridge, intersecttwo panels, then join the upper chord at an intermediate panel point,all points of intersection being on a curved line. Similar letters applyto members similarto those in Fig. 1. The center panel has two crosscounter braces G.

In Fig. 3 is-seen another adaptation of the improved truss to alongspan. Here the main diagonals D beginning with the centerjoint of lowerchord intersect three panels before they join the upper chord at anintermediate panel point, all intersections being on a curved line. Themain inclined braces D in this case, are held,in position by the counterbraces G at intersection with verticals as described in Fig. 1. Thistruss may be made of iron, steel or a combination of wood with iron orsteel and is applicable for bridges used for highways or railroads forspans of any length to which truss bridges are usually adapted, exceptthat the number of panels must not be less than six. 7

The truss is notacombination of an arched rib or suspension catenarywith a quadrangular or triangular truss as might be presumed from itsgeneral appearance, but is strictly a legitimate quadrangular ortriangular trusshaving some of its long panels subdivided into shorterpanels, the stress in each member being capable of accuratedetermination as in any regularly framed structure.

The inclined members D, which intersect two or more panels and havetheir connection joints with the verticals or chords on a curved line,are merely main braces or ties asin the case of a subdivided Pratttruss,but by being arranged in the broken manner shown, they are capableof relieving the chords of a part of their stresses and tend towardeconomy of material. The truss however, may be considered as acombination of a bowstrin g truss with a quadrangular or triagular trussframe, in which the diagonals D forming the bow and the members includedbetween this bow make a complete short span bowstring truss, the ends ofwhich are connected directly to intermediate panel points of a trussframe. The prolongations of the chord of the bow at each end are trussedby the members 0, E, and these members beingjoined to the chord memberwhich intersects the crown of the bow will form aquadrangular trussedframe.

The superiority of my invention over trusses used in bridges as usuallyconstructed, is as follows:First, it will give a substantial structure,each member of which has determinate strains; second, the stresses inthe chords have less variation than usual, being in some cases uniformfrom end to end; third, a saving in material.

Having now practically described the nature of this my invention, andits application, I would here state that in setting out the na ture ofthe invention, I have shown certain special arrangements and adaptationsto a different number of panels. I wish it to be understood however,that although these forms, modes and arrangements illustrated, may beused to advantage, yet I do not limit my invention to the special casesshown, as the improvement may be carried out in other forms withoutdeparting from its spirit or scope, and that it is susceptible of manymodified forms, and will necessarily have to be varied to suit thevarying conditions in actual practice, and V I declare what I claim inrespect of the herein-described invention is 1. In the construction oftriangular or quadrangular trusses for bridges or other structures,theherein'described trusses having but one point of bearing on each pierthe main braces or ties of which begin at and take direct hold of onechord at the center joint or joints nearest the center, intersect two ormore panels, and end at and connect directly to the other chord atintermediate panel points, the intersecting points of said braces orties with the chords and vertical members of the truss being points on acurved line.

2. In the construction of quadrangular or triangular trusses for bridgesor other structures, the herein described main braces or ties D whichend at their intersections with the upper and lower chordsatintermediate panel points, and which in joining the two chordstogether form a segmental curve.

3. In the construction of quadrangular or triangular trusses for bridgesor other structures, the braces or ties D extending from chord to chordbut not beyond and which incline at an angle with each other and withthe chords which they intersect at intermediate panel points, incombination with the counter braces G.

4. In the construction of quadrangular or triangular trusses for bridgesor other structures, the combination of double or triple intersectionbraces or ties D, which begin directly at a joint in one chord and endat an intermediate panel point in another chord whose intersections withchords and verticals, are points on a curve, with upper chord A, lowerchord B, inclined members 0, verticals E and F, and counter braces G,all as shown and described.

5. In the construction of trusses for bridges or otherstructu res, thecombination of a bowstring truss with a quadrangular or triangular trussframe in which the apex or crown of the bow is directly connected to one.chord of the triangular or quadrangular truss frame and the string ofthe bow forms when prolonged a part of the other chord of thequadrangular or triangular truss frame.

6. In the construction of quadrangular or triangular trusses for bridgesroots or other structures, the herein described truss composed of abowstring truss of four or more panels in combination with the extendedchord of the bow for one or more panels at each end, the said extensionsbeing trussed by the frames formed by the members 0 and E, and theseframes beingheld in position by the chord or straining beam whichconnects directly to the crown of the bowstring truss as well as to theframes thereby forming a complete truss of a longer span than thebowstring truss and having but one support on each pier.

JOHN ED\VIN GREINER.

\Vi'tnesses:

P. H. IRWIN, FEL X R. SULLIVAN.

